A disk drive stores and retrieves data by positioning a magnetic read/write head over a rotating magnetic data storage disk. Referring to FIGS. 1a and 1b, a typical disk drive in prior art has a drive arm 104 with a slider 203 mounted thereon and a magnetic disk 101. The disk 101 is mounted on a spindle motor 102 which causes the disk 101 to spin and a voice-coil motor (VCM) 107 is provided for controlling the motion of the drive arm 104 with the slider 203 and thus controlling the slider 203 to move from track to track across the surface of the disk 101 to read data from or write data to the disk 101.
However, Because of the inherent tolerance (dynamic play) resulting from VCM that exists in the displacement of the slider 203, the slider 203 can not attain a fine position displacement adjustment.
To solve the above-mentioned problem, piezoelectric (PZT) micro-actuators are now utilized to modify the displacement of the slider. That is, the PZT micro-actuator corrects the displacement of the slider on a much smaller scale to compensate for the tolerance of VCM and the drive arm 104. It enables a smaller recording track width, increases the ‘tracks per inch’ (TPI) value by 50% of the disk drive unit (also increases the surface recording density).
Referring to FIG. 1d, a traditional PZT micro-actuator 205 comprises a ceramic U-shaped frame 297 which comprises two ceramic beams 207 with two PZT pieces (not shown) on each side thereof. With reference to FIGS. 1c and 1d, the PZT micro-actuator 205 is physically coupled to a suspension 213, and there are three electrical connection balls 209 (gold ball bonding or solder ball bonding, GBB or SBB) to couple the micro-actuator 205 to the suspension traces 210 in one side of the ceramic beam 207. In addition, there are four metal balls 208 (GBB or SBB) to couple the slider 203 to the suspension 213 for electrical connection. FIG. 2 shows a detailed process of inserting the slider 203 into the micro-actuator 205. The slider 203 is bonded with the two ceramic beams 207 at two points 206 by epoxy dots 212 so as to make the motion of the slider 203 independent of the drive arm 104 (See FIG. 1a).
When power supply is applied through the suspension traces 210, the PZT micro-actuator 205 will expand or contract to cause the U-shaped frame 297 to deform and then make the slider 203 move on the disk 101. Thus a fine position displacement adjustment can be attained.
However, the PZT micro-actuator 205 can only be used for the position displacement adjustment of a head gimbal assembly (HGA) 277 (see FIG. 1c), it cannot be used for flying height adjustment (FH adjustment) of the head gimbal assembly (HGA) 277. As is known to all, flying height is a very important parameter of disk drives. That is, if the flying height is too high, it will affect the ability of slider 203 to read data from or write data to the disk 101; on the contrary, if the flying height is too low, the slider 203 may scratch the disk 101 which will damage the slider 203 and/or the disk 101. In today's disk drive industry, with the rapid increase of disk drive capacity, the track pitch and the track width of disk drive become increasing narrow. Accordingly the flying height of the slider becomes lower, and a fine flying height adjustment for an HGA becomes ever more important.
Also, referring to FIG. 2, in the prior art, the HGA 277 with the micro-actuator 205 is very difficult to manufacture for the following reasons: first, inserting and bonding the slider 203 to the micro-actuator 205 is difficult. Secondly, the epoxy dot 212 is very difficult to control, if the length of the epoxy dot 212 is too long, it will affect the work performance of the micro-actuator 205, for example, the displacement is not enough; if the length of the epoxy dot 212 is too short, the bonding strength will not be enough and then the shock performance is poor. In addition, the epoxy dot 212 is also difficult to control. If the epoxy dot 212 is too high, the height of the epoxy dot 212 will stay on the front or back side of the slider 203. The epoxy dot 212 staying on the front side of the slider 203 will influence the slider 203 flying on the disk 101 and even damage the slider 203 or the disk 101; the epoxy dot 212 staying on the back side of the slider 203 will influence the GBB process of the slider 203.
Furthermore, the micro-actuator 205 has an additional mass which not only influences the static performance, but also the dynamic performance of the suspension 213, such as the resonance performance, so as to reduce resonance frequency and increase the gain of the suspension 213.
Also, the U-shaped frame 297 of the micro-actuator 205 are very brittle, resulting in poor shock performance. It is also a big problem that there is no effective solution to identifying potential micro crack(s) of the U-shaped frame 297. Furthermore, when a voltage is applied to the PZT micro-actuator during normal operation, the back and forth bending of the brittle micro-actuator 205 will generate particles, and influencing the work performance of the micro-actuator 205.
In the manufacture process of HGA 277, since the HGA 277 has a complex configuration, the slider 203 must be tilted when the slider 203 is bonded to the U-shaped frame 297, and the U-shaped frame 297 must be tilted when the U-shaped frame 297 with the slider 203 is bonded to the suspension 213. Both will influence the static attitude of the HGA 277 and accordingly increase the difficulty of manufacturing the HGA 277.
It is well known that polishing is an effective and widely used cleaning method for reducing the micro contamination in the air bearing surface (ABS) of the slider. However, this cleaning method cannot be used in the above-mentioned HGA 277 because it is easy to damage the U-shaped frame 297 of the micro-actuator 205.
Hence, it is desired to provide a micro-actuator, head gimbal assembly, disk drive and manufacturing method thereof which can attain both a fine flying height adjustment and a fine position displacement adjustment, and overcome the above-mentioned shortcomings.